External preparations for skin

ABSTRACT

The present invention is a skin treatment composition that characteristically contains an alkyl benzoate represented by the following general formula (1). 
     This provides a skin treatment composition that gives a refreshing sensation at the time of application and can contain drugs and ultraviolet absorbents in a stable manner. 
     Also, the present invention is a sunblock water-in-oil type emulsified cosmetic characteristically comprising an ester bond product of polyhydroxystearic acid represented by the following general formulas (2) or (3), alkyl benzoate represented by the following general formula (1), and an ultraviolet absorbent. 
     This provides a sunblock cosmetic consisting of a water-in-oil type emulsified composition that can contain an ultraviolet absorbent in a stable manner and exhibits a superior usability. 
                         
(In this formula, R denotes a branched or straight chain alkyl group having 8-15 carbon atoms.)
 
                         
(In this formula, R 1  and R 2  denote, independently of each other, a hydrogen atom or a lower alkyl group having 1-6 carbon atoms, a+b denotes an integer 1-30, and m denotes an integer 10-200.)
 
                         
(In this formula, R 1  and R 2  denote, independently of each other, a hydrogen atom or a lower alkyl group having 1-6 carbon atoms, a+b denotes an integer 1-30, and n denotes an integer 1-30.)

TECHNICAL FIELD

The present invention relates to a skin treatment composition. Morespecifically, the present invention relates to a skin treatmentcomposition that gives a refreshing sensation at the time of applicationand contains an oil component that can sufficiently dissolve slightlysoluble ultraviolet absorbents and drugs.

The present invention relates to a sunblock water-in-oil (W/O) typeemulsified cosmetic. More specifically, it relates to a water-in-oiltype emulsified sunblock cosmetic that is not sticky, gives a superiorrefreshing sensation at the time of application, and can containslightly soluble ultraviolet absorbents in a stable manner.

BACKGROUND ART

Many silicone oils that give a refreshing sensation at the time ofapplication have been developed and used in skin treatment compositions.

However, since ultraviolet absorbents and drugs do not dissolve well insilicone oils, the addition of hydrocarbon oil components in which drugsand ultraviolet absorbents dissolve well has been desired.

While the hydrocarbon oil components dissolve drugs and ultravioletabsorbents well, they have a problem in that stickiness tends to resultwith higher blend ratios.

In view of the aforementioned problem, the inventors conducted earnestresearch and discovered that alkyl benzoate having a specific structurecan be added to a skin treatment composition to provide a skin treatmentcomposition that gives a superior refreshing sensation at the time ofapplication, and can contain drugs and ultraviolet absorbents in astable manner, and thus completed the present invention.

The object of the present invention is to provide a skin treatmentcomposition that gives a superior refreshing sensation at the time ofapplication and can contain slightly soluble ultraviolet absorbents anddrugs in a stable manner.

In a sunblock cosmetic consisting of a water-in-oil type emulsifiedcomposition, the oil phase is the continuous phase (outer phase).Therefore, compared with a sunblock cosmetic consisting of aoil-in-water type emulsified composition, it has a higher resistance tomicroorganisms. Also, at the time of application, it leaves an oil filmwith a low moisture permeability that protects the skin from drying fora long time. Furthermore, it doesn't re-emulsify easily when exposed towater in situations including bathing, washing/cleaning, andperspiration. For these reasons, it is used as a base agent in sunblockcosmetics.

However, conventional sunblock cosmetics consisting of a water-in-oiltype emulsified composition must dissolve a large amount of a highlypolar ultraviolet absorbent in the oil phase, resulting in separationand aggregation over a period of time; hence there is the problem ofpoor long term stability.

Also, in terms of usability, compared with a oil-in-water type sunblockcosmetic, it has problems such as stickiness, oiliness, and poorspreadability.

In view of the aforementioned problems, what has been desired is thedevelopment of an oil component that has a superior ability to dissolvea highly polar ultraviolet absorbent and a water-in-oil typeemulsification base agent that can stably emulsify the oil phasecontaining an ultraviolet absorbent.

In view of the aforementioned problem, the inventors conducted earnestresearch and discovered that alkyl benzoate having a specific structurecan be used as an oil component to dissolve the ultraviolet absorbentand an ester bond product of polyhydroxystearic acid having a specificstructure can be used for the emulsifier to prepare a water-in-oil typeemulsified composition that gives a refreshing sensation withoutstickiness at the time of application and has superior long termstability, and thus completed the present invention.

The object of the present invention is to provide a sunblock cosmeticconsisting of a water-in-oil type composition that is not sticky, givesa refreshing sensation at the time of application, and can stablycontain a highly polar ultraviolet absorbent, which has been difficultto introduce in a stable manner.

DISCLOSURE OF INVENTION

[Invention Defined in Claims 1-2]

That is, the present invention provides a skin treatment compositionthat characteristically contains an alkyl benzoate represented by thefollowing general formula (1):

(In this formula, R denotes a branched or straight chain alkyl grouphaving 8-10 carbon atoms.)

Also, the present invention provides the aforementioned skin treatmentcomposition wherein the compound represented by the aforementionedgeneral formula (1) is 3,7-dimethyloctyl benzoate.

[Invention Defined in Claims 3-7]

That is, the present invention provides a sunblock water-in-oil typeemulsified cosmetic characteristically comprising an ester bond productof polyhydroxystearic acid represented by the following general formula(2), alkyl benzoate represented by the following general formula (1),and an ultraviolet absorbent.

(In this formula, R¹ and R² denote, independently of each other, ahydrogen atom or a lower alkyl group having 1-6 carbon atoms, a+bdenotes an integer 1-30, and m denotes an integer 10-200.)

(In this formula, R denotes a branched or straight chain alkyl grouphaving 8-15 carbon atoms.)

Also, the present invention provides a sunblock water-in-oil typeemulsified cosmetic characteristically comprising an ester bond productof polyhydroxystearic acid represented by the following general formula(3), alkyl benzoate represented by the following general formula (1),and an ultraviolet absorbent.

(In this formula, R¹ and R² denote, independently of each other, ahydrogen atom or a lower alkyl group having 1-6 carbon atoms, a+bdenotes an integer 1-30, and n denotes an integer 1-30.)

(In this formula, R denotes a branched or straight chain alkyl grouphaving 8-15 carbon atoms.)

Furthermore, the present invention provides a sunblock water-in-oil typeemulsified cosmetic characteristically comprising an ester bond productof polyhydroxystearic acid represented by the following general formulas(2) and (3), alkyl benzoate represented by the following general formula(1), and an ultraviolet absorbent.

(In this formula, R¹ and R² denote, independently of each other, ahydrogen atom or a lower alkyl group having 1-6 carbon atoms, a+bdenotes an integer 1-30, and m denotes an integer 10-200.)

(In this formula, R¹ and R² denote, independently of each other, ahydrogen atom or a lower alkyl group having 1-6 carbon atoms, a+bdenotes an integer 1-30, and n denotes an integer 1-30.)

(In this formula, R denotes a branched or straight chain alkyl grouphaving 8-15 carbon atoms.)

Also, the present invention provides a sunblock water-in-oil typeemulsified cosmetic wherein R in the compound represented by theaforementioned general formula (1) denotes a branched or straight chainalkyl group having 8-10 carbon atoms.

Furthermore, the present invention provides the aforementioned sunblockwater-in-oil type emulsified cosmetic additionally containing anultraviolet scattering agent.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a ¹³C NMR spectrum of synthesis example 1.

FIG. 2 shows a ¹³C NMR spectrum of synthesis example 2.

FIG. 3 shows a ¹³C NMR spectrum of synthesis example 3.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is described in detail below.

[Invention Defined in Claims 1-2]

In general formula (1), R denotes a branched or straight chain alkylgroup having 8-10 carbon atoms; preferable are branched alkyl groupshaving 8-10 carbon atoms, and more preferable are branched alkyl groupshaving 10 carbon atoms.

If R is an alkyl group having seven or less carbon atoms, thenvolatility and odor cause problems. If R is an alkyl group having 11 ormore carbon atoms, then the refreshing sensation at the time ofapplication is degraded, which is not preferable.

Specific examples of the alkyl benzoate that satisfies general formula(1) include octyl benzoate, 2-ethylhexyl benzoate, 3,5,5-trimethylhexylbenzoate, and 3,7-dimethyloctyl benzoate. Of these, 3,7-dimethyloctylbenzoate is particularly preferable because of the sensation at the timeof application, solubility of ultraviolet absorbents and drugs, andodorlessness; it gives a skin treatment composition that gives asuperior refreshing sensation on the skin and can easily containultraviolet absorbents and drugs.

The alkyl benzoate of general formula (1) can be prepared by reacting analcohol having an alkyl group with a target number of carbon atoms andbenzoyl chloride in the presence of triethylamine, using chloroform asthe solvent; the reaction formula is shown below and the yield is 90% orhigher.

The blend ratio of the alkyl benzoate in the skin treatment compositionis not limited in particular. The blend ratio is usually 0.001-50% (masspercentage), preferably 0.1-30.0% (mass percentage), of the total amountof the skin treatment composition. If it is less than 0.001%, then theeffect of the addition is not manifested; if it is more than 50.0%, thena sticky sensation may result after application.

The skin treatment composition of the present invention is prepared byblending the aforementioned essential ingredient into an existing skintreatment composition base agent. In addition to the aforementionedessential ingredients, other ingredients used in skin treatmentcompositions can be blended as necessary in the skin treatmentcomposition of the present invention; examples of such ingredientsinclude powder ingredients, liquid fats and oils, solid fats and oils,waxes, hydrocarbons, higher fatty acids, higher alcohols, esters,silicones, anionic surfactants, cationic surfactants, ampholyticsurfactants, nonionic surfactants, humectants, water-soluble polymers,thickeners, coating agents, ultraviolet absorbents, sequestering agents,lower alcohols, polyhydric alcohols, sugars, amino acids, organicamines, polymer emulsions, pH adjusting agents, skin nutrients,vitamins, antioxidants, antioxidation assistants, perfumes, and water;and the skin treatment composition can be prepared for the targetformulation with a conventional method. Specific ingredients which canbe blended in are listed below. The skin treatment composition of thepresent invention can be prepared by blending the aforementionedessential ingredients and any one, two or more of the followingingredients.

Examples of the ultraviolet absorbents include the following ultravioletabsorbents.

A: Triazine-type Ultraviolet Absorbents

For example, bisresorsinyl triazine. More specifically,bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)1,3,5-triazine,2,4,6-tris{4-(2-ethylhexyloxycarbonyl)anilino}1,3,5-triazine, etc.

B: Benzoic Acid-type Ultraviolet Absorbents

For example, p-aminobenzoic acid (hereafter abbreviated as PABA), PABAmonoglycerin ester, N,N-dipropoxy PABA ethyl ester, N,N-diethoxy PABAethyl ester, N,N-dimethyl PABA ethyl ester, N,N-dimethyl PABA butylester, and N,N-dimethyl PABA ethyl ester.

C: Anthranilic Acid-type Ultraviolet Absorbents

For example, homo mentyl-N-acetyl anthranilate.

D: Salicylic Acid-type Ultraviolet Absorbents

For example, amyl salicylate, mentyl salicylate, homo mentyl salicylate,octyl salicylate, phenyl salicylate, benzyl salicylate, andp-isopropanol phenyl salicylate.

E: Cinnamic Acid-type Ultraviolet Absorbents

For example, octyl cinnamate, ethyl-4-isopropyl cinnamate,methyl-2,5-diisopropyl cinnamate, ethyl-2,4-diisopropyl cinnamate,methyl-2,4-diisopropyl cinnamate, propyl-p-methoxy cinnamate,isopropyl-p-methoxy cinnamate, isoamyl-p-methoxy cinnamate,octyl-p-methoxy cinnamate (2-ethylhexyl-p-methoxy cinnamate),2-ethoxyethyl-p-methoxy cinnamate, cyclohexyl-p-methoxy cinnamate,ethyl-α-cyano-β-phenyl cinnamate, 2-ethylhexyl-α-cyano-β-phenylcinnamate, and glyceryl mono-2-ethyl hexanoyl-di-p-methoxy cinnamate.

F: Other Ultraviolet Absorbents

For example, 3-(4′-methylbenzylidene)-d, 1-camphor, 3-benzylidene-d,1-camphor, 2-phenyl-5-methyl benzoxazol, 2-(2′-hydroxy-5′-methylphenyl)benzotriazol, 2-(2′-hydroxy-5′-t-octylphenyl) benzotriazol,2-(2′-hydroxy-5′-methylphenyl benzotriazol, dibenzaladine,dianisoylmethane, and 4-methoxy-4′-t-butyl dibenzoyl-methane,5-(3,3-dimethyl-2-norbornylidene)-3-pentane-2-one.

Examples of the powder ingredients include inorganic powders (forexample, talc, kaolin, mica, sericite, muscovite, phlogopite, syntheticmica, lepidolite, biotite, vermiculite, magnesium carbonate, calciumcarbonate, aluminum silicate, barium silicate, calcium silicate,magnesium silicate, strontium silicate, tungstic acid metal salt,magnesium, silica, zeolite, barium sulfate, firing calcium sulfate(calcined gypsum), calcium phosphate, fluorine-apatite, hydroxy apatite,ceramic powder, metallic soaps (for example, myristic acid zinc, calciumpalmitate, and aluminum stearate), and boron nitride; organic powders(for example, polyamide resin powder (nylon powder), polyethylenepowder, poly methyl methacrylate powder, polystyrene powder, powders ofcopolymer resin of styrene and acrylic acid, benzoguanamine resinpowder, polytetrafluoroethylene powder, and cellulose powder); inorganicwhite pigments (for example, titanium dioxide and zinc oxide); inorganicred pigments (for example, iron oxide (red iron oxide) and irontitanate); inorganic brown pigments (for example, γ-iron oxide);inorganic yellow pigments (for example, yellow iron oxide and loess);inorganic black pigments (for example, black iron oxide and low oxidesof titanium); inorganic purple pigments (for example, manganese violet,cobalt violet); inorganic green pigments (for example, chromium oxide,chromium hydroxide, and cobalt titanate); inorganic blue pigments (forexample, ultramarine blue and Berlin blue); pearl pigment (for example,titania coated mica, titania coated bismuth oxychloride, titania coatedtalc, coloration titania coated mica, bismuth oxychloride, fish scaleflakes); metal powder pigments (for example, aluminium powder, copperpowder); organic pigments such as Zr, barium or aluminium rake (forexample, organic pigments such as red 201, red 202, red 204, red 205,red 220, red 226, red 228, red 405, orange 203, orange 204, yellow 205,yellow 401 and blue 404, as well as red 3, red 104, red 106, red 227,red 230, red 401, red 505, orange 205, yellow 4, yellow 5, yellow 202,yellow 203, green 3 and blue 1; and natural colors (for example,chlorophyll and β-carotene).

Examples of the liquid fats and oils include avocado oil, tsubaki oil,turtle fatty acid, macademia nut oil, corn oil, mink oil, olive oil,rapeseed oil, egg yolk oil, sesame oil, persic oil, wheat germ oil,sasanqua oil, castor oil, linseed oil, safflower oil, cotton seed oil,perilla oil, soybean oil, peanut oil, tea seed oil, Japanese nutmeg oil,rice bran oil, Chinese gimlet oil, Japanese gimlet oil, jojoba oil, germoil, and triglycerin.

Examples of the solid fats and oils include cacao butter, coconut oil,hydrogenated coconut oil, palm oil, palm kernel oil, Japanese core waxnucleus oil, hydrogenated oil, Japanese core wax, and hydrogenatedcastor oil.

Examples of the waxes include beeswax, candelilla wax, cotton wax,carnauba wax, bayberry wax, tree wax, whale wax, montan wax, bran wax,lanolin, kapok wax, lanolin acetate, liquid lanolin, sugar cane wax,lanolin fatty acid isopropyl ester, hexyl laurate, reduced lanolin,jojoba wax, hard lanolin, shellac wax, POE lanolin alcohol ether, POElanolin alcohol acetate, POE cholesterol ether, lanolin fatty acidpolyethylene glycol, and POE hydrogenated lanolin ethyl alcohol ether.

Examples of the hydrocarbon oils include liquid petrolatum, ozocerite,squalane, pristane, paraffin, ceresin, squalene, petrolatum, andmicrocrystallin wax.

Examples of the higher fatty acids include lauric acid, myristic acid,palmitic acid, stearic acid, behenic acid, oleic acid, undecylenic acid,tall oil fatty acid, isostearic acid, linolic acid, linoleic acid,eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).

Examples of the higher alcohols include straight chain alcohols (forexample, lauryl alcohol, cetyl alcohol, stearyl alcohol, behenylalcohol, myristyl alcohol, oleyl alcohol, and cetostearyl alcohol) andbranched chain ethyl alcohols (for example, mono stearyl glycerin ether(batyl alcohol), 2-decyltetradecynol, lanolin alcohol, cholesterol,phytosterol, hexyl dodecanol, iso stearyl alcohol, and octyl dodecanol).

Examples of the ester oils include isopropyl myristate, cetyl octanoate,octyl dodecyl myristate, isopropyl palmitate, butyl stearate, hexyllaurate, myristil myristate, decyl oleate, dimethyl hexyl decyloctanoate, cetyl lactate, myristil lactate, lanolin acetate, iso cetylstearate, iso cetyl isostearate, cholesteryl hydroxy 12-stearate,ethylene glycol di-2-ethylhexanoate, dipentaerythritol fatty acid ester,n-alkylene glycol monoisostearate, neopentyl glycol dicaprate,diisostearyl malate, glyceryl di-2-heptylundecanoate, trimethylolpropanetri-2-ethylhexanoate, trimethylolpropane triisostearate,tetra-2-pentaerythritol ethylhexanoate, glycerin tri-2-ethylhexanoate,glyceryl trioctanoate, glycerin triisopalmitate, trimethylolpropanetriisostearate, cetyl 2-ethyl hexanoate, 2-ethylhexyl palmitate,glycerin trimyristate, tri-2-heptyl undecanoic acid glyceride, methylcastor oil fatty acid, oleyl oleate, aceto glyceride, 2-heptyl undecylpalmitate, diisobutyl adipate, 2-octyldodecyl N-lauroyl-L-glutamate,di-2-heptyl undecyl adipate, ethyl laurate, di-2-ethylhexyl sebacate,2-hexyl decyl myristate, 2-hexyldecyl palmitate, 2-hexyl decyl adipate,diisopropyl sebacate, 2-ethylhexyl succinate, and triethyl citrate.

Examples of the silicone oils include chain polysiloxanes (for example,dimethylpolysiloxane, methylphenyl polysiloxane, and diphenylpolysiloxane); ring polysiloxanes (for example,octamethylcyclotetrasiloxane, decamethyl cyclopenta siloxane, anddodecamethyl cyclohexa siloxane), silicone resins forming athree-dimensional network structure, silicone rubbers, and variousmodified polysiloxanes (amino-modified polysiloxane, polyether-modifiedpolysiloxane, alkyl-modified polysiloxane, and fluorine-modifiedpolysiloxane).

Examples of the anionic surfactants include fatty acid soaps (forexample, sodium laurate and sodium palmitate); higher alkyl sulfuricester salts (for example, sodium lauryl sulfate and potassiumlaurylsulfate); alkylether sulfuric ester salts (for example,POE-triethanolamine laurylsulfate and sodium POE-lauryl sulfate); N-acylsarcosinic acids (for example, sodium N-lauroyl sarcosinate); higherfatty acid amidosulfonic acid salts (for example, sodiumN-myristoyl-N-methyl taurate, sodium N-cocoyl N-methyl taurid, andsodium lauryl methyl taurid); phosphate ester salts (sodium POE-oleylether phosphate, POE-stearyl ether phosphoric acid, etc.);sulfosuccinates (for example, sodium di-2-ethylhexylsulfosuccinate,sodium mono lauroyl mono ethanol amide polyoxyethylene sulfosuccinate,and sodium lauryl polypropylene glycol sulfosuccinate); alkylbenzenesulfonates (for example, sodium linear dodecylbenzenesulfonate,triethanolamine linear dodecylbenzenesulfonate, and lineardodecylbenzenesulfonic acid); higher fatty acid ester sulfates (forexample, hydrogenated coconut oil aliphatic acid glycerin sodiumsulfate); N-acyl glutamates (for example, mono sodiumN-lauroylglutamate, disodium N-stearoylglutamate, and monosodiumN-myristoyl-L-glutamate); sulfated oils (for example, turkey red oil);POE-alkyl ether carboxylic acid; POE-alkylaryl ether carboxylate;α-olefin sulfonate; higher fatty acid ester sulfonates; sec-alcoholsulfates; higher fatty acid alkyl amide sulfates; sodium lauroylmonoethanolamine succinates; ditriethanolamine N-palmitoylaspartate; andsodium case mate.

Examples of the cationic surfactants include alkyltrimethylammoniumsalts (for example, stearyltrimethylammonium chloride andlauryltrimethyl ammonium chloride) alkylpyridinium salts (for example,cetylpyridinium chloride), distearyldimethylammonium chloridedialkyldimethylammonium salt; poly(N,N′-dimethyl-3,5-methylenepiperidinium) chloride; alkyl quaternary ammonium salts; alkyldimethylbenzyl ammonium salts; alkyl isoquinolinium salts;dialkylmorpholine salts; POE alkyl amines; alkyl amine salts; polyaminefatty acid derivatives; amylalcohol fatty acid derivatives; benzalkoniumchloride; and benzethonium chloride.

Examples of the ampholytic surfactants include: imidazoline typeampholytic surfactants (for example, 2-undecyl-N,N,N-(hydroxyethylcarboxymethyl)-2-imidazoline sodium salt and 2-coco yl-2-imidazoliniumhydroxide-1-carboxyethyloxy 2 sodium salt); and betaine type surtactants(for example, 2-heptadecyl-n-carboxymethyl-n-hydroxyethyl imidazoliniumbetaine, lauryldimethylaminoacetic acid betaine, alkyl betaine, amidebetaine, and sulfobetaine).

Examples of the lipophilic nonionic surface active agent includesorbitan fatty acid esters (for example, sorbitan monooleate, sorbitanmonoisostearate, sorbitan mono laurate, sorbitan monopalmitate, sorbitanmonostearate, sorbitan sesquioleate, sorbitan trioleate, diglycerolsorbitan penta-2-ethylhexylate, diglycerol sorbitantetra-2-ethylhexylate); glycerin polyglycerin aliphatic acids (forexample, mono-cottonseed oil fatty acid glycerin, glyceryl monoerucate,glycerin sesquioleate, glyceryl monostearate, α,α′-glyceryl oleatepyroglutamate, and glyceryl mono stearate malate); propylene glycolfatty acid esters (for example, propylene glycol monostearate);hydrogenated castor oil derivatives; and glycerin alkylethers.

Examples of the hydrophilic nonionic surface active agents include:POE-sorbitan fatty acid esters (for example, POE-sorbitan monooleate,POE-sorbitan monostearate, POE-sorbitan monoolate, and POE-sorbitantetraoleate); POE sorbitol fatty acid esters (for example, POE sorbitolmonolaurate, POE-sorbitol monooleate, POE-sorbitol pentaoleate, andPOE-sorbitol monostearate); POE-glycerin fatty acid esters (for example,POE-monooleates such as POE-glycerin monostearate, POE-glycerinmonoisostearate, and POE-glycerin triisostearate); POE-fatty acid esters(for example, POE-distearate, POE-monodioleate, and ethylene glycoldistearate); POE-alkylethers (for example, POE-lauryl ether, POE-oleylether, POE-stearyl ether, POE-behenyl ether, POE-2-octyl dodecyl ether,and POE-cholestanol ether); POE/POP-alkylethers (for example,POE/POP-cetyl ether, POE/POP-2-decyl tetradecyl ether, POE/POP-monobutylether, POE/POP-lanolin hydrate, and POE/POP-glycerin ether); POE-castoroil hydrogenated castor oil derivatives (for example, POE-castor oil,POE-hydrogenated castor oil, POE-hydrogenated castor oilmonoisostearate, POE-hydrogenated castor oil triisostearate,POE-hydrogenated castor oil monopyroglutamic monoisostearic diester, andPOE-hydrogenated castor oil maleic acid); POE-beeswax/lanolinderivatives (for example, POE-sorbitol beeswax); alkanol amides (forexample, coconut fatty acid diethanol amide, lauric acid monoethanolamide, and aliphatic acid isopropanol amide); POE-propylene glycol fattyacid esters; POE-alkyl amine; POE-fatty acid amide; sucrose fatty acidester; alkyl ethoxy dimethylamine oxides; and trioleyl phosphoric acid.

Examples of the humectant include polyethylene glycol, propylene glycol,glycerin, 1,3-butylene glycol, xylitol, sorbitol, maltitol, chondroitinsulfate, hyaluronic acid, mucoitin sulfuric acid, charonic acid,atelocollagen, cholesteryl-12-hydroxy stearate, sodium lactate, bilesalt, dl-pyrrolidone carboxylic acid salt, short chain soluble collagen,diglycerin (EO)PO adduct, chestnut rose fruit extract, yarrow extract,and sweet clover extract.

Examples of the natural water-soluble polymer include: plant-typepolymers (for example, gum arabic, gum tragacanth, galactan, guar gum,carob gum, karaya gum, carrageenan, pectin, agar, quince seed (Cydoniaoblonga), algae colloids (brown algae extract), starches (rice, corn,potato, and wheat), and glycyrrhizic acid); microorganism-type polymers(for example, xanthan gum, dextran, succinoglucan, and pullulan); andanimal-type polymers (for example, collagen, casein, albumin, andgelatin).

Examples of the semisynthetic water-soluble polymers include:starch-type polymers (for example, carboxymethyl starch andmethylhydroxypropyl starch); cellulosic polymers (for example, methylcellulose, ethyl cellulose, methylhydroxypropyl cellulose, hydroxyethylcellulose, cellulose sodium sulfate, hydroxypropyl cellulose,carboxymetyl-cellulose, sodium carboxymethyl cellulose, crystalcellulose, and cellulose powder); and alginic acid-type polymers (forexample, sodium alginate and propyleneglycol alginate).

Examples of the synthetic water-soluble polymers include: vinyl polymers(for example, polyvinyl alcohol, polyvinyl methyl ether,polyvinylpyrrolidone, carboxy vinyl polymer); polyoxyethylene-typepolymers (for example, a copolymer of polyethylene glycol 20,000,40,000, or 60,000 and polyoxyethylene polyoxypropylene); acrylicpolymers (for example, sodium polyacrylate, polyethylacrylate, andpolyacrylamide); polyethyleneimine; and cationic polymers.

Examples of the thickeners include: gum arabic, carrageenan, karaya gum,gum tragacanth, carob gum, quince seed (Cydonia oblonga), casein,dextrin, gelatin, sodium pectate, sodium arginate, methyl cellulose,ethyl cellulose, CMC, hydroxy ethyl cellulose, hydroxypropyl cellulose,PVA, PVM, PVP, sodium polyacrylate, carboxy vinyl polymer, locust beangum, guar gum, tamarind gum, cellulose dialkyl dimethylammonium sulfate,xanthan gum, aluminum magnesium silicate, bentonite, hectorite, AlMgsilicate (beagum), laponite, and silicic acid anhydride.

Examples of the sequestering agents include: 1-hydroxyethane-1,1-diphosphonic acid, 1-hydroxy ethane-1,1-diphosphonic acidtetrasodium salt, disodium edetate, trisodium edetate, tetrasodiumedetate, sodium citrate, sodium polyphosphate, sodium metaphosphate,gluconic acid, phosphoric acid, citric acid, ascorbic acid, succinicacid, and trisodium ethylenediaminehydroxyethyl triacetate.

Examples of the lower alcohols include ethanol, propanol, isopropanol,isobutyl alcohol, and t-butyl alcohol.

Examples of the polyhydric alcohols include: dihydric alcohols (forexample, ethylene glycol, propylene glycol, trimethylene glycol,1,2-butylene glycol, 1,3-butylene glycol, tetramethylene glycol,2,3-butylene glycol, pentamethylene glycol, 2-butene-1,4-diol, hexyleneglycol, and octylene glycol); trihydric alcohols (for example, glycerinand trimethylolpropane); tetrahydric alcohols (for example,pentaerythritols such as 1,2,6-hexanetriol); pentahydric alcohols (forexample, xylitol); hexahydric alcohols (for example, sorbitol,mannitol); polyhydric alcohol polymers (for example, diethylene glycol,dipropylene glycol, triethylene glycol, polypropylene glycol,tetraethylene glycol, diglycerin, polyethylene glycol, triglycerin,tetraglycerin, and polyglycerin); dihydric alcohol alkylethers (forexample, ethylene glycol monomethyl ether, ethylene glycol monoethylether, ethylene glycol monobutyl ether, ethylene glycol monophenylether, ethylene glycol monohexyl ether, ethylene glycol mono 2-methylhexyl ether, ethylene glycol isoamyl ether, ethylene glycol benzylether, ethylene glycol isopropyl ether, ethylene glycol dimethylether,ethylene glycol diethyl ether, and ethylene glycol dibutyl ether);dihydric alcohol ether esters (for example, ethylene glycol monomethylether acetate, ethylene glycol monoethyl ether acetate, ethylene glycolmonobutyl ether acetate, ethylene glycol monophenyl ether acetate,ethylene glycol diadipate, ethylene glycol disuccinate, diethyleneglycol monoethyl ether acetate, diethylene glycol monobutyl etheracetate, propylene glycolmonomethyl ether acetate, propylene glycolmonoethyl ether acetate, propylene glycol monopropyl ether acetate, andpropylene glycol monophenyl ether acetate); glycerin mono alkyl ethers(for example, xylyl alcohol, selachyl alcohol, and batyl alcohol); sugaralcohols (for example, sorbitol, maltitol, maltotriose, mannitol,sucrose, erythritol, glucose, fructose, starch amylolysis sugar,maltose, xylitose, and alcohol prepared by the reduction of starchamylolysis sugar); glysolid; tetrahydro furfuryl alcohol; POE-tetrahydrofurfuryl alcohol; POP-butyl ether; POP/POE-butyl ether;tripolyoxypropylene glycerin ether; POP-glycerin ether, POP-glycerinether phosphoric acid; POP/POE-pentane erythritol ether, andpolyglycerin.

Examples of the monosaccharides include: trioses (for example,D-glyceryl aldehyde and dihydroxyacetone); tetroses (for example,D-etythrose, D-erythrulose, D-threose, and erythritol); pentoses (forexample, L-arabinose, D-xylose, L-lyxose, D-arabinose, D-ribose,D-ribulose, D-xylulose, and L-xylulose); hexoses (for example,D-glucose, D-talose, D-psicose, D-galactose, D-fructose, L-galactose,L-mannose, and D-tagatose); heptoses (for example, aldoheptose andheprose); octoses (for example, octurose); deoxysugars (for example,2-deoxy-D-ribose, 6-deoxy-L-galactose, and 6-deoxy-L-mannose); aminosugars (for example, D-glucosamine, D-galactosamine, sialic acid, aminouronic acid, and muramic acid); and uronic acid (for example,D-glucuronic acid, D-mannuronic acid, L-guluronic acid, D-galacturonicacid, and L-iduronic acid).

Examples of the oligosaccharides include sucrose, umbelliferose,lactose, planteose, isolignoses, α,α-trehalose, raffinose, lignoses,umbilicine, stachyose and verbascose.

Examples of the polysaccharides include cellulose, quince seed,chondroitin sulfate, starch, galactan, dermatan sulfate, glycogen, gumarabic, heparan sulfate, hyaluronic acid, traganth gum, keratan sulfate,chondroitin, xanthan gum, mucoitin sulfuric acid, guar gum, dextran,kerato sulfate, locustbean gum, succinoglucane, and charonic acid.

Examples of the amino acids include neutral amino acids (for example,threonine and cysteine) and basic amino acids (for example,hydroxylysine). Examples of the amino acid derivatives include sodiumacyl sarcosinate (sodium N-lauroyl sarcosinate), acyl glutamate, sodiumacyl β-alanine, glutathione, and pyrrolidone carboxylic acid.

Examples of the organic amines include monoethanolamine, diethanolamine,triethanolamine, morpholine, triisopropanolamine,2-amino-2-methyl-1,3-propanediol, and 2-amino-2-methyl-1-propanol.

Examples of the high polymer emulsions include acrylic resin emulsions,ethyl polyacrylate emulsions, acryl resin liquids, polyacrylic alkylester emulsions, polyvinyl acetate resin emulsions, and natural rubberlatex.

Examples of the pH adjustment agents include buffers such as lacticacid-sodium lactate, citric acid-sodium citrate, and succinicacid-sodium succinate.

Examples of the vitamins include vitamins A, B1, B2, B6, C and E as wellas their derivatives, pantothenic acid and its derivatives, and biotin.

Examples of the antioxidants include tocopherols, dibutylhydroxytoluene, butyl hydroxyanisole, and gallic ester.

Examples of the antioxidation auxiliary agents include phosphoric acid,citric acid, ascorbic acid, maleic acid, malonic acid, succinic acid,fumaric acid, cephalin, hexameta phosphate, phytic acid, and ethylenediamine tetraacetic acid.

Examples of other possible ingredients include antiseptics(ethylparaben, butylparaben, etc.); anti-inflammatory agents (forexample, glycyrrhizic acid derivatives, glycyrrhetinic acid derivatives,salicylic acid derivatives, hinokitiol, zinc oxide, and allantoin);whitening agents (for example, placenta extract, creeping saxifrageextract and arbutin); various extracts (for example, PhellodendriCortex, goldthread, lithospermum root, Paeonia lactiflora, Swertiajaponica, Birch, sage, loquat, carrot, aloe, Malva sylvestris, Iris,grape, Coix ma-yuen, sponge gourd, lily, saffron, Cnidium officinale,sheng jiang, Hypericum erectum, Ononis, garlic, Guinea pepper, chen pi,Ligusticum acutilobum, and seaweed), activators (royal jelly,photosensitive substances, and cholesterol derivatives); bloodcirculation promoting agents (for example, nonyl acid valenyl amide,nicotinic acid benzyl esters, nicotinic acid β-butoxy ethyl esters,capsaicin, gingeron, cantharis tincture, Ichthammol, tannic acid,α-borneol, tocopherol nicotinate, inositol hexanicotinate, cyclandelate,cinnarizine, tolazoline, acetylcholine, verapamil, cepharanthine, andã-orizanol); anti-seborrhea agents (for example, sulfur and thiantol);and antiinflammatory agents (for example, tranexamic acid, thiotaurine,and hypotaurine).

Ultraviolet absorbents and drugs can be blended into the skin treatmentcomposition of the present invention in a stable manner. Therefore, itis preferable to blend in slightly soluble ultraviolet absorbents orslightly soluble drugs that are hard to be blend stably in aconventional oil component due to poor solubility.

Examples of the ultraviolet absorbents preferably blended into the skintreatment composition of the present invention include triazine-typeultraviolet absorbents which do not dissolve easily in conventional oilcomponents. For example, an ultraviolet absorbent such as bisresorsinyltriazine is preferably blended in. More specifically,2,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)1,3,5-triazineand 2,4,6-tris{4-(2-ethylhexyloxycarbonyl)anilino}1,3,5-triazine, usedby the name of octyl triazone are preferably blended in.

Any formulation can be used including the solution type, the solubilizedtype, emulsion type, powder dispersion type, water-oil bilayer type, andwater-oil-powder three layer type. The product form of the skintreatment composition of the present invention is arbitrary. It can beused in lotions, emulsions, creams, facial cosmetics such as packs,makeup cosmetics such as foundations, lipsticks, and eye shadows, bodycosmetics, aroma cosmetics, cleaners, and ointments.

For blending in ultraviolet absorbents and/or drugs, emulsions andcream-like emulsified compositions are preferable from the point of viewof usability.

[Invention Defined in Claims 3-7]

The compound of general formula (2) is an ester bond product ofpolyhydroxystearic acid prepared by the ester polymerization ofpolyethylene glycol and hydroxystearic acid; it acts as an emulsifier inthe present invention.

Preferable specific examples of general formula (2) are those for whichm is 10-100, more preferably 20-60, and a+b is 3-20, more preferably5-15.

The compound of general formula (3) is an ester bond product ofpolyhydroxystearic acid prepared by the ester polymerization ofpolyglycerin and hydroxystearic acid; it acts as an emulsifier in thepresent invention.

Preferable specific examples of general formula (3) are those for whichn is 1-30, more preferably 3-10, and a+b is 3-20, more preferably 5-15.Specific compounds that can be used preferably are decaglycerinpentaisostearate and tetraglycerin pentastearate.

In the compounds of general formulas (2) and (3), R¹ and R²,independently of each other, denote a hydrogen atom or a lower alkylgroup having 1-6 carbon atoms.

Examples of the lower alkyl group having 1-6 carbon atoms include bothstraight chains and branched chains such as a methyl group, ethyl group,propyl group, isopropyl group, butyl group, sec-butyl group, tert-butylgroup, pentyl group, isopentyl group, neopentyl group, tert-pentylgroup, and hexyl group.

A specific example of the compound of general formula (2) iscommercially available as Aracel P135 (from ICI Surfactants).

Also, a specific example of the compound of general formula (3) iscommercially available as Dehymuls PGPH (from CognisDeutschland GmbH),which is polyglyceryl-2 dipolyhydroxyhisstearate for which R¹ and R² areboth hydrogen atoms.

In the present invention, one, two or more of the compounds that satisfythe aforementioned general formula (2) are used for the emulsifier. Inthe sunblock water-in-oil type emulsified cosmetic of the presentinvention, the compound of general formula (2) manifests an exceptionalemulsifying ability and thus is capable of providing a sunblock cosmeticwith superior emulsification stability. Since a sunblock cosmetic can beleft unattended under severe summer conditions, the exceptionalemulsification stability manifested by the present invention is a veryuseful effect.

The blend ratio of the compound that satisfies general formula (2) ispreferably 0.1-5.0% (mass percentage), more preferably 0.5-2.0%, of thewater-in-oil type emulsified composition. If it is less than 0.1%, thenthe oil phase portion in which the ultraviolet absorbent is dissolvedcannot be emulsified stably for a long time; if it is more than 5.0%,then spreading on the skin tends to become poor. Because of the superioremulsifying ability, a blend ratio of 0.5-2.0% (mass percentage) canprovide a sunblock cosmetic that has superior emulsification stabilityand no problem in terms of spreading on the skin.

Also, one, two or more of the compounds that satisfy the aforementionedgeneral formula (3) are used for the emulsifier. In the sunblockwater-in-oil type emulsified cosmetic of the present invention,introduction of the compound of general formula (3) makes it possible toprovide a sunblock cosmetic that is particularly superior in terms ofspreading on the skin. Since a sunblock cosmetic is spread all over theskin, the use of the compound of general formula (3) as an emulsifier inthe present invention results in a sunblock cosmetic that is superior interms of the ultraviolet prevention effect on the entire skin due togood spreadability that allows homogeneous application on the entireskin and helps prevent missed areas.

The blend ratio of the compound that satisfies general formula (3) ispreferably 0.1-5.0% (mass percentage), more preferably 0.5-4.0%, of thewater-in-oil type emulsified composition. If it is less than 0.1%, thenthe oil phase portion in which the ultraviolet absorbent is dissolvedcannot be emulsified stably for a long period; if it is more than 5.0%,then stickiness may arise.

Furthermore, in the present invention, joint use of one, two or more ofthe compounds that satisfy general formula (2) and one, two or more ofthe compounds that satisfy the aforementioned general formula (3) isparticularly preferable in view of superior emulsification stability andspreadability.

When the compound that satisfies general formula (2) and the compoundthat satisfies general formula (3) are used jointly, the total blendratio of the two is preferably 0.1-5.0% (mass percentage). If it is lessthan 0.1%, then the oil phase portion in which the ultraviolet absorbentis dissolved cannot be emulsified stably for a long period; if it ismore than 5.0%, then stickiness and/or poor spreadability may result.

The relative blend ratio of the compound of general formula (2) and thecompound of general formula (3) is determined according to the recipe ofthe sunblock cosmetic; a preferable mass ratio is Compound of generalformula (2): Compound of general formula (3)=1:1 to 1:2. For the blendratio of each compound, the blend ratio of the compound of generalformula (2) is preferably 0.5-1.5% (mass percentage) and the blend ratioof the compound of general formula (3) is preferably 0.5-2.0% (masspercentage).

Emulsifiers other than those described above can also be added withinthe range that does not spoil the effects of the present invention;however, there is no substantial need for such addition.

The alkyl benzoate having a specific structure that is used as an oilcomponent to dissolve the ultraviolet absorbent is described below.

The alkyl benzoate used in the present invention is represented by theaforementioned general formula (1). In general formula (1), R denotes abranched or straight chain alkyl group having 8-15 carbon atoms. Alkylgroups having six or less carbon atoms are volatile and also problematicdue to the odor; alkyl groups having 16 or more carbon atoms spoil therefreshing sensation at the time of application. Preferable are straightchain or branched alkyl groups having 8-10 carbon atoms, more preferableis a 3,7-dimethyloctane group, for which R has 10 carbon atoms.

Preferable examples of the alkyl benzoate of general formula (1) includeoctyl benzoate, 2-ethylhexyl benzoate, 3,5,5-trimethylhexyl benzoate,and 3,7-dimethyloctyl benzoate. Of these, 3,7-dimethyloctyl benzoate isparticularly preferable in terms of the sensation at the time ofapplication, solubility of the ultraviolet absorbent, and a lack ofodor.

The alkyl benzoate of general formula (1) can be prepared by reacting analcohol with an alkyl group having a target number of carbons andbenzoyl chloride in the presence of triethylamine, using chloroform asthe solvent; the reaction formula is shown below and the yield is 90% orhigher.

Also, alkyl benzoates having 12-15 carbon atoms are commerciallyavailable as well. For example, Crodamol AB (from Croda, Inc.), which isa mixture of alkyl groups having 12-15 carbon atoms, are commerciallyavailable.

The blend ratio of the alkyl benzoate is not limited in particular;usually it is 0.1-50.0% (mass percentage), more preferably 0.5-30.0%(mass percentage), of the water-in-oil type emulsified composition. Ifit is less than 0.1%, then the effect of dissolving the ultravioletabsorbent is not manifested; if it is more than 50.0%, then a stickysensation may result.

The following compounds are examples of the ultraviolet absorbent usedin the present invention.

A: Triazine-type Ultraviolet Absorbents

For example, bisresorsinyl triazine.

More specifically,bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)1,3,5-triazine,2,4,6-tris{4-(2-ethylhexyloxycarbonyl)anilino}1,3,5-triazine, etc.

B: Benzoic Acid-type Ultraviolet Absorbents

For example, p-aminobenzoic acid (hereafter abbreviated as PABA), PABAmonoglycerin ester, N, N-dipropoxy PABA ethyl ester, N,N-diethoxy PABAethyl ester, N,N-dimethyl PABA ethyl ester, N,N-dimethyl PABA butylester, and N,N-dimethyl PABA ethyl ester.

C: Anthranilic Acid-type Ultraviolet Absorbents

For example, homo mentyl-N-acetyl anthranilate.

D: Salicylic Acid-type Ultraviolet Absorbents

For example, amyl salicylate, mentyl salicylate, homo mentyl salicylate,octyl salicylate, phenyl salicylate, benzyl salicylate, andp-isopropanol phenyl salicylate.

E: Cinnamic Acid-type Ultraviolet Absorbents

For example, octyl cinnamate, ethyl-4-isopropyl cinnamate,methyl-2,5-diisopropyl cinnamate, ethyl-2,4-diisopropyl cinnamate,methyl-2,4-diisopropyl cinnamate, propyl-p-methoxy cinnamate,isopropyl-p-methoxy cinnamate, isoamyl-p-methoxy cinnamate,octyl-p-methoxy cinnamate (2-ethylhexyl-p-methoxy cinnamate),2-ethoxyethyl-p-methoxy cinnamate, cyclohexyl-p-methoxy cinnamate,ethyl-α-cyano-β-phenyl cinnamate, 2-ethylhexyl-α-cyano-β-phenylcinnamate, and glyceryl mono-2-ethyl hexanoyl-di-p-methoxy cinnamate.

F: Other Ultraviolet Absorbents

For example, 3-(4′-methylbenzylidene)-d, 1-camphor, 3-benzylidene-d,1-camphor, 2-phenyl-5-methyl benzoxazol, 2-(2′-hydroxy-5′-methylphenyl)benzotriazol, 2-(2′-hydroxy-5′-t-octylphenyl) benzotriazol,2-(2′-hydroxy-5′-methylphenyl benzotriazol, dibenzaladine,dianisoylmethane, and 4-methoxy-4′-t-butyl dibenzoyl-methane,5-(3,3-dimethyl-2-norbornylidene)-3-pentane-2-one.

It is particularly preferable to use a highly polar triazine-typeultraviolet absorbent, such as bisresorsinyl triazine. Morespecifically,2,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)1,3,5-triazineand 2,4,6-tris{4-(2-ethylhexyloxycarbonyl)anilino}1,3,5-triazine, usedby the name of octyl triazone are preferably blended in.

The blend ratio of the ultraviolet absorbent is not limited inparticular, but usually 0.01-30.0% (ultraviolet absorbent) of thewater-in-oil type emulsified composition is preferable. The blend ratiois determined based on the target ultraviolet absorption effect (SPFvalue).

Since the sunblock cosmetic of the present invention can dissolveslightly soluble highly polar ultraviolet absorbents that are difficultto introduce in a stable manner, a desired ultraviolet absorbent can beintroduced at a desired blend ratio. Therefore, sunblock cosmetics thatare superior in emulsification stability, have a high ultravioletabsorption effect and improved SPF value can be provided. Since evenslightly soluble drugs can be dissolved in a stable manner, it is alsopreferable to introduce slightly soluble drugs according to the purpose.

In the present invention, it is preferable to further introduce anultraviolet scattering agent (ultraviolet protection powder).

Examples of the ultraviolet scattering agent include the powders oftitanium oxide, fine particle titanium oxide, zinc oxide, fine particlezinc oxide, iron oxide, fine particle iron oxide, and cerium oxide. Thepowder used is usually in the form of needles, cones, spheres andgranules. Fine particle powder having a particle size of 0.1 micrometersor less is preferable.

Ultraviolet scattering agents prepared by hydrophobicizing these powdersare also preferable. Examples include powders treated with silicone byusing methylhydrogen polysiloxane, silane coupling agents and such,powders treated with metal soap, powders treated with fluoride by usingdiethanolamine perfluoroalkylphosphate, perfluoroalkylsilane and such,and powders treated with dextrin fatty acid ester.

The blend ratio of the ultraviolet scattering agent is not limited inparticular. It is usually 0.5-50% (mass percentage), preferably 1-30%(mass percentage), of the total amount of the sunblock cosmetic. If theblend ratio is too high, it may not be preferable in terms of sensationat the time of application and stability.

In addition to the aforementioned essential ingredients, otheringredients used in skin treatment compositions can be blended in asnecessary in the skin treatment composition of the present invention;examples of such ingredients include powder ingredients, liquid fats andoils, solid fats and oils, waxes, hydrocarbons, higher fatty acids,higher alcohols, esters, silicones, anionic surfactants, cationicsurfactants, ampholytic surfactants, nonionic surfactants, humectants,water-soluble polymers, thickeners, coating agents, sequestering agents,lower alcohols, polyhydric alcohols, sugars, amino acids, organicamines, polymer emulsions, pH adjusting agents, skin nutrients,vitamins, antioxidants, antioxidation assistants, perfumes, and water;and the skin treatment composition can be prepared for the targetformulation with a conventional method. Specific possible ingredientsare the same as the aforementioned possible ingredients for the skintreatment composition. The aforementioned essential ingredients and anyone, two or more of the aforementioned ingredients are blended in toprepare the sunblock cosmetic of the present invention.

The formulation of the sunblock cosmetic of the present invention is anwater-in-oil type emulsified composition; preferable examples areemulsion and/or cream type sunblock cosmetics.

EXAMPLES

The present invention is described in detail below by referring toExamples. The present invention is not limited to these examples. First,synthesis examples of the alkyl benzoate used in the present inventionare described.

Synthesis Example 1 3,7-dimethyloctyl benzoate (isodecyl benzoate)

Chloroform (300 mL) was put into an argon-substituted 2 L three-neckflask and benzoyl chloride (100 mL, 0.86 mol) was added, followed bystirring at room temperature. Subsequently, 3,7-dimethyloctanol (246 mL,1.3 mol) was dripped in, and, after the temperature was lowered to 0° C.with ice, triethylamine (120 mL, 0.86 mL) was dripped in, and six hoursof stirring was carried out as the temperature was gradually raised toroom temperature. Unreacted benzoyl chloride was quenched by adding 100mL of water, followed by rinsing with 200 mL of 0.1 N hydrochloric acidand drying with sodium sulfate; the solvent was then removed underreduced pressure. The obtained orange colored oil-like product wasdistilled under a reduced pressure of 0.5 mmHg to obtain a colorless,odorless oil-like compound (yield 82%). The structure was verified using¹³C NMR; 3,7-dimethyloctyl benzoate with the following structuralformula was obtained. FIG. 1 shows the ¹³C NMR spectrum. The IOB valueof the obtained oil component is 0.23.

Synthesis Example 2 3,5,5-trimethylhexyl benzoate (isononyl benzoate)

Chloroform (300 mL) was put into an argon-substituted 2 L three-neckflask and benzoyl chloride (100 mL, 0.86 mol) was added, followed bystirring at room temperature. Subsequently, 3,5,5-trimethyl-1-hexanol(225 mL, 1.3 mol) was dripped in, and, after the temperature was loweredto 0° C. with ice, triethylamine (120 mL, 0.86 mL) was dripped in andsix hours of stirring was carried out as the temperature was graduallyraised to room temperature. Unreacted benzoyl chloride was quenched byadding 100 mL of water, followed by rinsing with 200 mL of 0.1 Nhydrochloric acid and drying with sodium sulfate; the solvent was thenremoved under reduced pressure. The obtained orange colored oil-likeproduct was distilled under a reduced pressure of 0.5 mmHg to obtain acolorless oil-like compound (yield 85%). The structure was verifiedusing ¹³C NMR; 3,5,5-trimethylhexyl benzoate with the followingstructural formula was obtained. FIG. 2 shows the ¹³C NMR spectrum. TheIOB value of the obtained oil component is 0.26.

Synthesis Example 3 2-ethylhexyl benzoate

Chloroform (300 mL) was put into an argon-substituted 2 L three-neckflask and benzoyl chloride (100 mL, 0.86 mol) was added, followed bystirring at room temperature. Furthermore, 2-ethyl-1-hexanol (202 mL,1.3 mol) was dripped in, and, after the temperature was lowered to 0° C.with ice, triethylamine (120 mL, 0.86 mL) was dripped in and six hoursof stirring was carried out as the temperature was gradually raised toroom temperature. Unreacted benzoyl chloride was quenched by adding 100mL of water, followed by rinsing with 200 mL of 0.1 N hydrochloric acidand drying with sodium sulfate; the solvent was then removed underreduced pressure. The obtained orange colored oil-like product wasdistilled under a reduced pressure of 0.5 mmHg to obtain a colorlessoil-like compound (yield 83%). The structure was verified using ¹³C NMR;2-ethylhexyl benzoate with the following structural formula wasobtained. FIG. 3 shows the ¹³C NMR spectrum. The IOB value of theobtained oil component is 0.26.

[Examples of the Sunblock Cosmetics of Claim 1 and Claim 2]

The alkyl benzoates obtained in the aforementioned synthetic examples1-3 were added to a skin treatment composition and evaluated. The blendratios are in % (mass-percentage) units unless specified otherwise.

The testing method and the evaluation method are described first.

“Evaluation (1): Refreshing Sensation on the Skin”

The refreshing sensation on the skin during use was evaluated withactual use testing by ten specialized panelists. The evaluation criteriaare as follows:

-   ⊚ . . . Eight or more specialized panelists reported a refreshing    sensation on the skin during use.-   ◯ . . . Six or more and less than eight specialized panelists    reported a refreshing sensation on the skin during use.-   Δ . . . Three or more and less than six specialized panelists    reported a refreshing sensation on the skin during use.-   X . . . Less than three specialized panelists reported a refreshing    sensation on the skin during use.    “Evaluation (2): Non-stickiness on the Skin”

The non-stickiness on the skin during use was evaluated with actual usetesting by ten specialized panelists. The evaluation criteria are asfollows:

-   ⊚ . . . Eight or more specialized panelists reported non-stickiness    on the skin during use.-   ◯ Six or more and less than eight specialized panelists reported    non-stickiness on the skin during use.-   Δ . . . Three or more and less than six specialized panelists    reported non-stickiness on the skin during use.-   X . . . Less than three specialized panelists reported    non-stickiness on the skin during use.    “Evaluation (3): Solubility of the Ultraviolet Absorbent”

A solubility test of a slightly soluble ultraviolet absorbent (triazinederivative) at a low temperature (0° C.) was carried out.

Examples 1-1 to 1-8, Comparative Examples 1-1 to 1-3

Skin treatment compositions (O/W type emulsion) consisting of the blendcomposition described in Table 1-1, Table 1-2, and Table 1-3 wereprepared with a conventional method and the aforementioned evaluationtest was conducted. The results are shown in the tables. The evaluationtest results for the aforementioned evaluation (3) are shown in Table1-4.

TABLE 1-1 Examples Ingredients 1-1 1-2 1-3 1-4 3,7-dimethyloctyl 0.0010.1 1.0 5.0 benzoate Sodium hexamethaphosphate 0.01 0.01 0.01 0.01Trisodium edetate 0.03 0.03 0.03 0.03 1,3-butylene glycol 5 5 5 5Potassium hydroxide 0.1 0.1 0.1 0.1 Carboxyvinyl polymer 0.1 0.1 0.1 0.1Preservative 0.15 0.15 0.15 0.15 Purified water Balance Balance BalanceBalance Evaluation (1): Refreshing ◯ ⊚ ⊚ ⊚ sensation on the skinEvaluation (2): ◯ ⊚ ⊚ ⊚ Non-stickiness on the skin

TABLE 1-2 Examples Ingredients 1-5 1-6 1-7 2-ethylhexyl benzoate 5 — —3,5,5-trimethylhexyl — 5 — benzoate 3,7-dimethyloctyl benzoate — — 5Sodium hexamethaphosphate 0.01 0.01 0.01 Trisodium edetate 0.03 0.030.03 1,3-butylene glycol 5 5 5 Potassium hydroxide 0.1 0.1 0.1Carboxyvinyl polymer 0.1 0.1 0.1 Preservative 0.15 0.15 0.15 Purifiedwater Balance Balance Balance Evaluation (1): Refreshing ⊚ ⊚ ⊚ sensationon the skin Evaluation (2): ⊚ ⊚ ⊚ Non-stickiness on the skin

TABLE 1-3 Example Comparative examples Ingredients 1-8 1-1 1-2 1-33,7-dimethyloctyl benzoate 5 — — — Decamethyl cyclopentane — 5 — —siloxane Isocetyl oleate — — 5 — Liquid petrolatum — — — 5 Sodiumhexamethaphosphate 0.01 0.01 0.01 0.01 Trisodium edetate 0.03 0.03 0.030.03 1,3-butylene glycol 5 5 5 5 Potassium hydroxide 0.1 0.1 0.1 0.1Carboxyvinyl polymer 0.1 0.1 0.1 0.1 Preservative 0.15 0.15 0.15 0.15Purified water Balance Balance Balance Balance Evaluation (1):Refreshing ⊚ ⊚ ⊚ ◯ sensation on the skin Evaluation (2): ⊚ ⊚ ⊚ ⊚Non-stickiness on the skin

The solubility of a slightly soluble ultraviolet absorbent in the alkylbenzoate obtained in synthetic examples 1-3 was measured. For theslightly soluble ultraviolet absorbent, a triazine-type ultravioletabsorbent2,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)1,3,5-triazinewas used.

The solubility is expressed as a concentration (mass percentage) in asaturated solution at 0° C.

For the alkyl benzoate having 12-15 carbon atoms, a commercial product(Crodamol AB from Croda, Inc.) was used. This oil component is a mixtureof alkyl benzoates having 12-15 carbon atoms.

The alkyl benzoate used in the skin treatment composition of the presentinvention is shown to have a distinctively increased ability to dissolveslightly soluble drugs, compared with alkyl benzoates having 12-15carbon atoms and other oil components.

Furthermore, 3,7-dimethyloctyl benzoate turned out to be an excellentoil component without any odor.

TABLE 1-4 Oil components Solubility 2-ethylhexyl benzoate 12%  (Carbonnumber 8) 3,5,5-trimethylhexyl benzoate 13%  (Carbon number 9)3,7-dimethyloctyl benzoate 12%  (Carbon number 10) Alkyl benzoate 8%(Carbon number 12–15) Di-2-ethylhexyl succinate 4% Pentaerythrite tetra(2- 4% ethylhexanoate/paramethoxycinnamate) Decamethyl cyclopentanesiloxane 0% Liquid petrolatum 0%

The results above show that the skin treatment compositions of thepresent invention exhibit superior effects for all the evaluation items.That is, as an oil component to be added to a skin treatmentcomposition, the specific alkyl benzoates used in the present inventionare comparably excellent in terms of giving a refreshing sensation andno stickiness, compared with conventional oil components. Furthermore,since the ability to dissolve slightly soluble ultraviolet absorbents isalso high, a skin treatment composition with a desired blend ratio ofslightly soluble ultraviolet absorbents or drugs can be provided. Inparticular, the alkyl benzoates having 10 carbon atoms are odorless andfunction as an excellent oil component for a skin treatment composition.

Other Examples of the skin treatment composition of the presentinvention are shown below.

Example 1-9 Sunblock Emulsion

A. Oil Phase

Volatile cyclic silicone    27.0% (Decamethyl cyclopentane siloxane)Silicone-hydrophobicized titanium dioxide 10.0 Silicone-hydrophobicizedzinc oxide 10.0 Silicone-hydrophobicized talc  4.0 3,7-dimethyloctylbenzoate (synthetic example 1) 10.0 Octylmethoxy cinnamate  5.04-methoxy-4′-t-butyl dibenzoyl-methane  2.02,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-  3.0(4-methoxyphenyl)1,3,5-triazine Organically modified montmorillonite 0.5 Preservative Appropriate amount Perfume Appropriate amount(Preparation Method and Evaluation)

The oil phase and the water phase are each mixed and dissolved.Dispersion of titanium dioxide in the oil phase portion is thoroughlyconducted, to which the water phase portion is added, and emulsificationis carried out using a homogenizer. The obtained sunblock emulsion issuperior in terms of a refreshing sensation. It is also superior interms of stable dissolution of the slightly soluble ultravioletabsorbent2,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)1,3,5-triazine.

Example 1-10 Sunblock Cream

A. Oil Phase

Stearic acid    10.0% Stearyl alcohol  4.0 Butyl stearate  8.0Monoglycerin stearate  2.0 Vitamin E acetate  0.5 Vitamin A palmitate 0.1 3,7-dimethyloctyl benzoate 10.0 (synthetic example 1)2,4-bis{[4-(2-ethylhexyloxy)-2-  3.0 hydroxy]phenyl}-6-(4-methoxyphenyl)1,3,5-triazine Macadamia nut oil  1.0 Tea seed oil  3.0 Perfume  0.4Preservative Appropriate amountB. Water Phase

Glycerin 4.0 1,2 pentane diol 3.0 Sodium hyaluronate 1.0 Potassiumhydroxide 2.0 Magnesium ascorbate phosphate 0.1 L-arginine hydrochloride0.01 Trisodium edetate 0.05 Purified water Balance(Preparation Method and Evaluation)

Oil phase A and water phase B are each heated up to 70° C. to bedissolved completely. The A phase is added to the B phase, followed byemulsification by means of an emulsifier. The emulsion is cooled by aheat exchanger to obtain a cream. The obtained cleansing oil exhibitssuperior smoothness, no stickiness, and sustained moisture retention. Itis also superior in terms of stable dissolution of the slightly solubleultraviolet absorbent2,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)1,3,5-triazine.

Example 1-11 Cream

A. Oil Phase

Cetanol     4.0% Petrolatum  7.0 Isopropyl myristate  8.0 Squalane 10.03,7-dimethyloctyl benzoate 10.0 (synthetic example 1)2,4-bis{[4-(2-ethylhexyloxy)-2-  3.0 hydroxy]phenyl}-6-(4-methoxyphenyl)1,3,5-triazine Monoglycerin stearate  2.2 POE(20) sorbitan monostearate 2.8 3,7-dimethyloctyl benzoate 20.0 (synthetic example 1) Vitamin Enicotinate  2.0 Perfume  0.3 Antioxidant Appropriate amount PreservativeAppropriate amountB. Water Phase

Glycerin 10.0 Sodium hyaluronate 0.02 Dipropylene glycol 4.0 Sodiumpyrrolidone carboxylate 1.0 Disodium edetate 0.01 Purified water Balance(Preparation Method and Evaluation)

Oil phase A and water phase B are each heated up to 70° C. to bedissolved completely. The A phase is added to the B phase, followed byemulsification by means of an emulsifier. The emulsion is cooled by aheat exchanger to obtain a cream. The obtained cream exhibits superiorsmoothness, no stickiness, and sustained moisture retention. It is alsosuperior in terms of stable dissolution of the slightly solubleultraviolet absorbent2,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)1,3,5-triazine.

Example 1-12 Foundation

A. Oil Phase

Cetanol    3.5% Deodorized lanolin 4.0 Jojoba oil 5.0 Petrolatum 2.0Squalane 6.0 Monoglycerin stearate 2.5 POE(60) hydrogenated castor oil1.5 POE(20) cetyl ether 1.0 3,7-dimethyloctyl benzoate 2.0 (syntheticexample 1) Pyridoxine tripalmitate 0.1 Preservative Appropriate amountPerfume 0.3B. Water Phase

Propylene glycol 10.0 Powder preparation 12.0 Trisodiumethylenediaminehydroxyethyl  1.0 triacetate Purified water Balance(Preparation Method and Evaluation)

Oil phase A and water phase B are each heated up to 70° C. to bedissolved completely. The A phase is added to the B phase, followed byemulsification by means of an emulsifier. The emulsion is cooled by aheat exchanger to obtain an emulsified foundation. This emulsifiedfoundation is a cream that exhibits superior smoothness, no stickiness,superior refreshing sensation, and sustained moisture retention. It isalso superior in terms of stable dissolution of the slightly solubleultraviolet absorbent2,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)1,3,5-triazine.

Example 1-13 W/O Sunblock (Cream)

Ingredients

Blend ratio Material (mass percentage) Water Ion-exchanged water BalanceHumectant 1,3-butylene glycol 5.0 Chelating agent EDTA-3Na 2H₂OAppropriate amount Activator Condensed PEG-1500 hydroxystearate 0.5Condensed diglyceryl hydroxystearate 1.5 Oil component Isodecyl benzoate1.0 Dineopentanoic acid tripropylene glycol 4.5 Dineopentanoic acidtripropylene glycol 1.5 Cetyl 2-ethylhexanoate 3.0 Diglycerol sorbitantetra-2-ethylhexanoate 5.0 Decamethylcyclopentasiloxane 10.0Trimethylsiloxy silicic acid - 4.5 decamethylcyclopentasiloxane solution(50%) 3,7-dimethyloctyl benzoate 7.0 UV absorbent Octylmethoxy cinnamate7.5 Uvinul T150 (registered trademark) from BASF 1.0 Bisresorcinyltriazine {TINOSORB S 3.0 (registered trademark) from Ciba Specialty} UVscattering agent Hydrophobicized silica-coated zinc oxide 15.0(Preparation Method and Evaluation)

The ingredients are mixed and emulsified with a conventional method toobtain a W/O sunblock (cream). The obtained sunblock (cream) is superiorin terms of refreshing sensation. It is also superior in terms ofdissolution stability of ultraviolet absorbents.

Example 1-14 W/O Sunscreen (Emulsion)

Water Ion-exchanged water Balance Humectant Dynamite glycerin 5.0Thickener Succinoglycan 0.35 Carboxymethyl cellulose Na salt 0.15Activator POE(100) hydrogenated castor oil 1.5 Scattering agentCondensed PEG-1500 hydroxystearate 0.5 Decamethylcyclopentasiloxane 5.0Oil component Cetyl 2-ethylhexanoate 2.0 Glyceryl tri-2-ethylhexanoate3.0 Isostearic acid 1.0 3,7-dimethyloctyl benzoate 5.0 UV absorbentOctylmethoxy cinnamate 5.0 Uvinul T150 (registered trademark) from BASF2.0 Bisresorcinyl triazine {TINOSORB S 3.0 (registered trademark) fromCiba Specialty} UV protection agent Hydrophobicized silica-coated zincoxide 15.0 Ethanol 5.0 Preservative Methylparaben Appropriate amount(Preparation Method and Evaluation)

The ingredients are mixed and emulsified with a conventional method toobtain a W/O sun protector (emulsion). The obtained sun protector(emulsion) is superior in terms of refreshing sensation. It is alsosuperior in terms of dissolution stability of ultraviolet absorbents.

[Examples of the Skin Treatment Compositions of Claims 3-7]

The solubility of a slightly soluble ultraviolet absorbent in the alkylbenzoate obtained in the aforementioned synthetic examples 1-3 wasmeasured. For the slightly soluble ultraviolet absorbent, atriazine-type ultraviolet absorbent2,4-bis{[4-(2-ethylhexyloxy)-2-hydroxy]phenyl}-6-(4-methoxyphenyl)1,3,5-triazinewas used.

The solubility is expressed as a concentration (mass percentage) in asaturated solution at 0° C.

For the alkyl benzoate having 12-15 carbon atoms, a commercial product(Crodamol AB from Croda, Inc.) was used. This oil component is a mixtureof alkyl benzoates having 12-15 carbon atoms.

TABLE 2-1 Oil components Solubility 2-ethylhexyl benzoate 12%  (Carbonnumber 8) 3,5,5-trimethylhexyl benzoate 13%  (carbon number 9)3,7-dimethyloctyl benzoate 12%  (Carbon number 10) Alkyl benzoate 8%(Carbon number 12-15) Di-2-ethylhexyl succinate 4% Pentaerythrite tetra(2- 4% ethylhexanoate/paramethoxycinnamate) Decamethyl cyclopentanesiloxane 0% Liquid petrolatum 0%

Table 2-1 shows that the alkyl benzoates having 8-10 carbon atoms have adistinctively increased ability to dissolve slightly soluble drugs.Furthermore, 3,7-dimethyloctyl benzoate, which has 10 carbon atoms,turned out to be an excellent oil component without any odor.

However, in the present invention, a water-in-oil type emulsifiedcomposition that allows stable dissolution of slightly solubleultraviolet absorbents at a desired blend ratio in the oil phase portionis expected to be obtained by preferably using alkyl benzoate having8-10 carbon atoms.

Examples 2-1 to 2-8, Comparative Examples 2-1 to 2-8

Next, sunblock cosmetics consisting of the water-in-oil type emulsifiedcompositions of Examples and Comparative examples shown in Table 2-2 andTable 2-3 were prepared and the following evaluations were conducted.The blend ratios are in % (mass percentage) units unless specifiedotherwise.

Manufacturing Methods of Examples 2-1 to 2-8 and Comparative Examples2-1 to 2-8

(1)-(11) are mixed and stirred to obtain a homogeneous oil phase. (12)and (13) are then added to this oil phase and stirred homogeneously witha homomixer to obtain the oil phase portion. Finally, (15), dissolved in(14), is gradually added to the oil phase portion as it is stirred withthe homomixer at room temperature (20° C.) to obtain a sunblock cosmetic(cream type).

“Refreshing Sensation on the Skin”

The refreshing sensation on the skin during use was evaluated withactual use testing by ten specialized panelists. The evaluation criteriaare as follows:

-   ⊚ . . . Eight or more specialized panelists reported a refreshing    sensation on the skin during use.-   ◯ . . . Six or more and less than eight specialized panelists    reported a refreshing sensation on the skin during use.-   Δ . . . Three or more and less than six specialized panelists    reported a refreshing sensation on the skin during use.-   X . . . Less than three specialized panelists reported a refreshing    sensation on the skin during use.    “Non-stickiness on the Skin”

The non-stickiness on the skin during use was evaluated with actual usetesting by ten specialized panelists. The evaluation criteria are asfollows:

-   ⊚ . . . Eight or more specialized panelists reported non-stickiness    on the skin during use.-   ◯ . . . Six or more and less than eight specialized panelists    reported non-stickiness on the skin during use.-   Δ . . . Three or more and less than six specialized panelists    reported non-stickiness on the skin during use.-   X . . . Less than three specialized panelists reported    non-stickiness on the skin during use.    “Stability”

The samples were put into thermostatic baths kept at 50° C., 25° C., and−5° C., and observed microscopically or visually after three months.

-   ⊚ . . . No anomaly is observed microscopically or visually.-   ◯ . . . No anomaly is observed visually but the microscopic    observation reveals slight separation or crystalline precipitation.-   Δ . . . Slight separation or crystalline precipitation is observed    visually or microscopically.-   X . . . Separation or crystalline precipitation is clearly observed    visually.    “Ultraviolet Prevention Effect Test”

A highly accurate in vitro SPF measuring system (a system that canmeasure SPF values and PFA values with high accuracy) described inJapanese Patent Laid-Open No. H7-167781 bulletin was used.

Specifically, a solar simulator (Solar Ultraviolet Simulator Model 600from Solar Light Co.) was used as the light source. 2.0 mg/cm² of thespecimen was evenly applied on Transpore Tape™ (3M Co.) and ultravioletlight was irradiated on it. The transmitted ultraviolet light spectrumwas processed to calculate the SPF value and the PFA value.

Table 2-2 and Table 2-3 show that Examples of the present invention aresunblock water-in-oil type emulsified cosmetics that have a highsunblock effect, give a refreshing sensation with no stickiness at thetime of application, and exhibit superior stability.

The sunblock cosmetics obtained by using 3,5,5-trimethylhexyl benzoateand 2-ethylhexyl benzoate of synthetic example 2 and synthetic example3, respectively, instead of 3,7-dimethyloctyl benzoate in Examples 2-1to 2-8, also are sunblock water-in-oil type emulsified cosmetics thathave a high sunblock effect, give a refreshing sensation with nostickiness at the time of application, and exhibit superior stability.

The sunblock cosmetics obtained by using tetraglycerin pentastearate ordecamethyl pentaisostearate of general formula (3) instead ofpolyethylene glycol dipolyoxystearate in Examples 2-1 to 2-8, also aresunblock water-in-oil type emulsified cosmetics that have a highsunblock effect, give a refreshing sensation with no stickiness at thetime of application, and exhibit superior stability.

TABLE 2-2 Examples Ingredient names 2-1 2-2 2-3 2-4 2-5 2-6 2-7 2-8  (1)— — — 15.0  — — — — Decamethylcyclopentasiloxane  (2)Dimethylpolysiloxane — — — — — — — — 6 mPa · s  (3) Di-2-ethylhexyl — —— — — 19.5  — — succinate  (4) 3,7-dimethyloctyl 20.0  20.0  20.0  5.030.0  0.5 20.0  20.0  benzoate  (5) Polyethylene glycol 2.0 — 1.0 2.02.0 2.0 7.0 0.5 dipolyhydroxystearate*¹  (6) Decaglycerin — 2.0 1.0 — —— — — pentaisostearate*²  (7) Polyether modified — — — — — — — —silicone*³  (8) Organically modified — — — — — — — — montmorillonite (9) Bisresorcinyl triazine*⁴ 3.0 3.0 3.0 1.0 5.0 3.0 3.0 0.1 (10)Octylmethoxy cinnamate 7.0 7.0 7.0 9.0 — 7.0 7.0 9.9 (11)Trimethylsiloxysilicic 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 acid*⁵ (12)Silicone- 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 hydrophobicized titaniumdioxide (13) Silicone- 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 hydrophobicizedzinc oxide (14) Ion-exchanged water 56.85 56.85 56.85 56.85 51.85 56.8551.85 58.35 (15) Methylparaben  0.15  0.15  0.15  0.15  0.15  0.15  0.15 0.15 Refreshing sensation ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯ ⊚ Non-stickiness ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ◯◯ Stability ⊚ ⊚ ⊚ ◯ ◯ ◯ ⊚ ◯ In Vitro SPF value 51.3  50.6  51.5  46.4 52.1  47.3  49.5  50.2  In Vitro PFA value 8.3 8.1 8.3 5.4 8.6 6.7 7.98.0 *¹In general formula (2) for this compound, a is 5, b is 5, m is 30,and R¹ and R² are H. *²In general formula (3) for this compound, a is 5,b is 5, n is 10, and R¹ and R² are H. *³Product name: KF6017, 50%solution of decamethylcyclopentasiloxane, from Shin-Etsu Chemical Co.,Ltd. *⁴Product name: TINOSORB S from Ciba Specialty *⁵Product name:KF7312J from Shin-Etsu Chemical Co., Ltd.

TABLE 2-3 Comparative examples Ingredient names 2-1 2-2 2-3 2-4 2-5 2-62-7 2-8  (1) 20.0  — 10.0  10.0  10.0  10.0  — —Decamethylcyclopentasiloxane  (2) Dimethylpolysiloxane — — — 5.0 5.0 — —— 6 mPa · s  (3) Di-2-ethylhexyl — — — 5.0 5.0 10.0  20.0  20.0 succinate  (4) 3,7-dimethyloctyl — 20.0  10.0  — — — — — benzoate  (5)Polyethylene glycol 2.0 — — 2.0 — 2.0 7.0 1.0 dipolyhydroxystearate*¹ (6) Decaglycerin — — — — 2.0 — — 1.0 pentaisostearate*²  (7) Polyethermodified — 1.0 1.0 — — — — — silicone*³  (8) Organically modified — 1.01.0 — — — — — montmorillonite  (9) Bisresorcinyl triazine*⁴ 3.0 3.0 3.03.0 — — 3.0 0.1 (10) Octylmethoxy cinnamate 7.0 7.0 7.0 7.0 10.0  10.0 7.0 9.9 (11) Trimethylsiloxysilicic 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0acid*⁵ (12) Silicone- 5.0 5.0 5.0 5.0 5.0 10.0  5.0 5.0 hydrophobicizedtitanium dioxide (13) Silicone- 5.0 5.0 5.0 5.0 5.0 10.0  5.0 5.0hydrophobicized zinc oxide (14) Ion-exchanged water 56.85 56.85 56.8556.85 56.85 46.85 51.85 57.0  (15) Methylparaben  0.15  0.15  0.15  0.15 0.15  0.15  0.15  0.15 Refreshing sensation ◯ ◯ ◯ ◯ ⊚ Δ ◯ ◯Non-stickiness ◯ Δ ◯ ◯ ⊚ Δ ◯ ⊚ Stability X X X Δ ◯ ⊚ X Δ In Vitro SPFvalue 38.3  50.6  41.5  45.4  32.1  47.3  49.5  50.2  In Vitro PFA value6.3 8.1 6.3 5.4 6.7 6.7 7.9 8.0 *¹In general formula (2) for thiscompound, a is 5, b is 5, m is 30, and R¹ and R² are H. *²In generalformula (3) for this compound, a is 5, b is 5, n is 10, and R¹ and R²are H. *³Product name: KF6017 from Shin-Etsu Chemical Co., Ltd.*⁴TINOSORB S from Ciba Specialty *⁵Product name: KF7312J from Shin-EtsuChemical Co., Ltd.

Other Examples of the present invention are shown below.

Example 2-9 Water-in-oil Type Sunblock Cosmetic

(emulsion type) % (Oil phase portion)  (1) Octyl-p-methoxycinnamate 5.0 (2) Oxybenzone 3.0  (3) 4-tert butyl-4′-methoxybenzoylmethane 1.0  (4)Silicone-hydrophobicized titanium dioxide 6.0  (5)Silicone-hydrophobicized zinc oxide 6.0  (6) Squalane 10.0  (7) Octylbenzoate 23.0  (8) Octamethylcyclotetrasiloxane 5.0  (9) Glycerintriisooctanoate 2.0 (10) Polyethylene glycol dipolyhydroxystearate 1.0  (Represented by general formula (2) wherein a is   15, b is 15, m is120, and R¹ and R² are methyl   groups.) (11) Bisresorcinyl triazin 3.0  (Product name: TINOSORB S from Ciba Specialty   Chemicals) (Waterphase portion) (12) Methylparaben 0.1 (13) Phenoxy ethanol 0.1 (14)Ion-exchanged water 29.8 (15) 1,3-butylene glycol 5.0Preparation Method

The ingredients of the oil phase portion and the water phase portion areseparately heated up to 70° C. and dissolved. Dispersion of titaniumdioxide in the oil phase is thoroughly conducted, to which the waterphase portion is added as emulsification is carried out using ahomogenizer. This emulsified composition is cooled with a heat exchangerto obtain an emulsion type water-in-oil type sunblock cosmetic having aviscosity of 8,000 MPa·s. The obtained sunblock cosmetic is refreshingand non-sticky; its SPF value is 50.1 and the PFA value is 8.8; and noanomaly is observed in the stability test after incubating for threemonths in thermostatic baths at −5° C., 25° C., and 50° C.

Example 2-10 Water-in-oil Type Sunblock Cosmetic

(cream type) % (Oil phase portion)  (1) Dextrin fatty acidester-hydrophobicized 7.0   titanium dioxide  (2)Silicone-hydrophobicized zinc oxide 10.0  (3)Decamethylcyclopentasiloxane 10.0  (4) 2-ethylhexyl benzoate 25.0  (5)Liquid petrolatum 10.0  (6) Glycerin triisooctanoate 3.0  (7)Tetraglycerin pentastearate 4.0  (8) Butylparaben 0.2  (9) Perfume 0.1(10) Ethyl-4-isopropyl cinnamate 5.0 (11) Bisresorcinyl triazine 1.5  (Product name: TINOSORB S from Ciba Specialty   Chemicals) (Water phaseportion) (12) Ion-exchanged water 21.7 (13) 1,3-butylene glycol 2.5(Preparation Method)

The ingredients of the oil phase portion and the water phase portion areseparately heated up to 70° C. and dissolved. Dispersion of titaniumdioxide in the oil phase was thoroughly conducted, to which the waterphase portion is added as emulsification is carried out using ahomomixer. This emulsified composition is cooled with a heat exchangerto obtain a water-in-oil type sunblock cosmetic having a viscosity of55,000 MPa·s.

The obtained sunblock cosmetic is refreshing and non-sticky; its SPFvalue is 49.2 and the PFA value is 8.3; and no anomaly is observed inthe stability test after incubating for three months in thermostaticbaths at −5° C., 25° C., and 50° C.

Example 2-11 Water-in-oil Type Sunblock Cosmetic

(emulsion type) % (Oil phase portion)  (1) Dimethylpolysiloxane (6 mPa ·s) 12.0  (2) 3,7-dimethyloctyl benzoate 25.0  (3) Liquid petrolatum 1.5 (4) Octylmethoxy cinnamate 7.0  (5) Ethylparaben 0.2  (6) Perfume 0.1 (7) Dextrin fatty acid ester-hydrophobicized zinc 6.0   oxide  (8)Polyethylene glycol dipolyhydroxystearate   (Represented by generalformula (2) wherein a is 7,   b is 7, m is 35, and R¹ and R² are H.)(Water phase portion)  (9) Ion-exchanged water 39.7 (10) Propyleneglycol 5.0 (12) Sodium glutamate 1.5 (13) Sodium chloride 0.5(Preparation Method)

The ingredients of the oil phase portion and the water phase portion areseparately heated up to 70° C. and dissolved. Dispersion of titaniumdioxide in the oil phase was thoroughly conducted, to which the waterphase portion is added as emulsification is carried out using ahomogenizer. This emulsified composition is cooled with a heat exchangerto obtain an emulsion type water-in-oil type sunblock cosmetic having aviscosity of 2000 MPa·s. The obtained sunblock cosmetic is refreshingand non-sticky; its SPF value is 42.4 and the PFA value is 6.8. Noanomaly is observed in the stability test after incubating for threemonths in thermostatic baths at −5° C., 25° C., and 50° C.

INDUSTRIAL APPLICABILITY

The alkyl benzoate having a specific structure used in the presentinvention is preferably used in a skin treatment composition as an oilcomponent that gives a refreshing sensation at the time of applicationand can contain drugs and ultraviolet absorbents in a stable manner.

The present invention can provide a skin treatment composition thatgives a superior refreshing sensation at the time of application and cancontain slightly soluble ultraviolet absorbents and drugs withoutdifficulty.

The sunblock cosmetic of the present invention, in spite of being awater-in-oil type emulsified composition, can contain a highly polarultraviolet absorbent in a stable manner and also gives an excellentrefreshing and non-sticky sensation at the time of application.

The present invention makes it possible to easily manufacture a sunblockcosmetic that can exhibit desired ultraviolet prevention effects,superior stability, and superior sensation at the time of application.

1. A skin treatment composition comprising an alkyl benzoate representedby the following general formula (1):

wherein R denotes a branched or straight chain alkyl group having 8-10carbon atoms.
 2. The skin treatment composition of claim 1 wherein thecompound represented by the aforementioned general formula (1) is3,7-dimethyloctyl benzoate.